Preservatives are ingredients that have anti-microbial activity that are frequently used in skincare or cosmetic products. Preservatives are aimed at protecting these products from decay or spoilage, so that these products are protected from decomposition and deterioration and remain stable for extended periods of time, in particular during the entire shelf-life of the products.
A disadvantage of using such agents is that they may cause adverse effects such as allergic responses and irritation. Examples of preservatives that are less tolerated especially at increased concentration, are the parabens and phenoxyethanol.
This is especially the case when applying cosmetic formulations containing preservatives to sensitive skin types such as in atopic skin types. This is the reason why so far, cosmetic formulations that can be applied to sensitive skin types (such as, e.g. atopic skin, baby skin, sun alterated skin, allergenic skin) contain less preservatives and therefore are prone to become affected and degraded by microorganisms and moreover to become a source of microbiological contamination.
Preservative agents should by preference be present in as low a concentration as possible. A limiting factor evidently is that the formulations need to be adequately protected. One would therefore be inclined to reduce the amount of preservative in cosmetic formulations, in particular in those formulations that are or can be used on sensitive skin types. By doing so, one could expect that the aforementioned side effects are reduced or even completely absent. However, this would result in the concentration of the preservative being too low to be effective, resulting in an unacceptable risk of the formulation becoming affected by microorganisms.
Therefore it would be desirable to provide formulations for skincare or cosmetic use that are sufficiently protected against microbiological contamination and are not susceptible to microbiological decay and deterioration. It would additionally be desirable to provide such formulations that are devoid of the adverse effects that are typically associated with the use of traditional preservative agents, in particular in the instance of application of cosmetic formulations to sensitive skin types.
Another reason for having low amounts of preservative agents in formulations is that these can interact with certain components present in the formulations, in particular with certain sensitive active ingredients. Certain formulation categories therefore are not easy to preserve. A particular product class is the self-tanning products, in particular those based on dihydroxyacetone (DHA), which is a component that is readily decomposed by physical as well as chemical causes. The presence of certain ingredients in DHA containing formulations promotes decay of this active ingredient and compromises the stability of DHA-based self-tanning formulations.
Hence there is a particular need to have preservative systems that are effective in self-tanning formulations based on DHA.
FR-2 834 459 describes the use of a combination of anisic acid, a salt or an alkyl ester thereof, a polyol and a cationic surfactant as an anti-microbial agent in cosmetic formulations, in particular in hair treatment compositions such as shampoos.
The formulations of the present invention are aimed to meet these needs. The use of a combination of anisic acid and certain fatty acid monoglycerides allows to reduce the amounts of preservative agents in skin care and cosmetic formulations and in particular allows to provide preservative systems in self-tanning formulations based on DHA.
Neither anisic acid nor glyceryl caprilate are currently used as preservatives. Anisic acid is used as fragrance and glyceryl caprilate is used as humectant and emollient.